Task Decomposer

Transforms ambiguous feature requests into concrete, implementable task sequences: identifies acceptance criteria, decomposes into phased work items with effort sizing, maps dependencies and parallelization, enumerates edge cases, plans testing, and flags risks — producing a ready-to-execute task board.

When to use this skill vs native decomposition: The base model decomposes features well in an ad-hoc format. Use this skill specifically when you need the structured output: phased task tables with dependency mapping, parallelization flags, risk flags, and integrated test strategy. If you just need a quick list of steps, ask directly without invoking this skill.

Reference Files

File	Contents	Load When
references/decomposition-patterns.md	Feature → task decomposition strategies, granularity guidelines	Always
references/edge-case-checklist.md	Common edge case categories by domain (web, API, data, CLI)	Edge case identification needed
references/dependency-mapping.md	Dependency graph construction, critical path identification	Multi-task breakdown
references/sizing-guide.md	Effort estimation guidance (S/M/L), complexity indicators	Effort sizing needed

Prerequisites

• Feature description or requirements (can be vague — the skill handles ambiguity)
• Project context (tech stack, existing architecture, team size)

Workflow

Phase 1: Understand the Feature

1. Extract the user-facing goal — What does this feature enable the user to do? If unclear, state assumptions explicitly.
2. Define acceptance criteria — What must be true for this feature to be "done"? Express as testable statements: "User can X", "System does Y when Z."
3. Identify non-functional requirements — Performance, security, accessibility, backwards compatibility constraints.
4. Clarify scope boundaries — What is explicitly out of scope? State this to prevent scope creep during implementation.

Phase 2: Decompose into Tasks

Break the feature into tasks at the right granularity:

Granularity	Size	Example
Too coarse	"Build the search feature"	Not actionable
Right level	"Add full-text search index to products table"	Single PR, testable
Too fine	"Import the search library"	Not independently meaningful

Right granularity test: Each task should be completable in a single PR, testable in isolation, and deliverable independently (even if not user-visible alone).

Group tasks into phases:

Phase	Purpose	Contains
Foundation	Data models, schemas, interfaces	Types, database tables, API contracts
Core logic	Business logic, algorithms	The actual feature implementation
Integration	Connecting components, API endpoints	Routes, controllers, wire-up
Polish	Edge cases, error handling, UX	Validation, error messages, loading states

Phase 3: Identify Edge Cases

For each task, enumerate edge cases:

1. Input boundaries — Empty, null, maximum size, special characters
2. State transitions — Concurrent modification, interrupted operations
3. Error conditions — Network failures, invalid data, permission denied
4. Backwards compatibility — Existing data, existing API consumers

Phase 4: Plan Testing

For each task, identify what to test:

Test Level	What to Test	Who Writes
Unit	Individual functions, pure logic	During implementation
Integration	Component interactions, API endpoints	After integration phase
Manual	User flows, visual correctness	After polish phase

Phase 5: Map Dependencies

Identify which tasks depend on others:

1. Hard dependencies — Task B requires Task A's output (database table must exist before writing queries)
2. Soft dependencies — Task B benefits from Task A but could use a stub
3. No dependency — Tasks can be done in parallel

Phase 6: Flag Risks

For each risk, identify mitigation:

Risk Type	Example	Mitigation
Technical unknown	"Never used WebSockets before"	Spike/prototype first
External dependency	"Requires API access we don't have"	Request early, use mocks
Scope uncertainty	"Requirements may change"	Implement core first, defer edge cases
Performance risk	"May be slow with 1M rows"	Add benchmark task, define acceptable threshold

Output Format

## Task Decomposition: {Feature Name}

### Feature Summary
{One paragraph describing what this feature does and why}

### Acceptance Criteria
- [ ] {Testable statement 1}
- [ ] {Testable statement 2}
- [ ] {Testable statement 3}

### Scope
- **In scope:** {what's included}
- **Out of scope:** {what's excluded}

### Task Breakdown

#### Phase 1: Foundation
| # | Task | Effort | Dependencies | Parallel |
|---|------|--------|--------------|----------|
| 1.1 | {task description} | {S/M/L} | None | Yes |
| 1.2 | {task description} | {S/M/L} | 1.1 | No |

#### Phase 2: Core Logic
| # | Task | Effort | Dependencies | Parallel |
|---|------|--------|--------------|----------|
| 2.1 | {task description} | {S/M/L} | 1.x | Yes |
| 2.2 | {task description} | {S/M/L} | 1.x | Yes |

#### Phase 3: Integration
| # | Task | Effort | Dependencies | Parallel |
|---|------|--------|--------------|----------|
| 3.1 | {task description} | {S/M/L} | 2.x | No |

#### Phase 4: Polish
| # | Task | Effort | Dependencies | Parallel |
|---|------|--------|--------------|----------|
| 4.1 | {task description} | {S/M/L} | 3.x | Yes |

### Edge Cases

| # | Edge Case | Handling | Phase |
|---|-----------|----------|-------|
| 1 | {edge case} | {how to handle} | {which phase} |

### Test Strategy

#### Unit Tests
- {Component}: {what to test}

#### Integration Tests
- {Flow}: {what to test}

#### Manual Verification
- {Scenario}: {what to check}

### Risk Flags
- {Risk}: {mitigation strategy}

Calibration Rules

1. Right granularity. Each task should be 1-3 days of work. Larger → decompose further. Smaller → merge into a parent task.
2. Testable acceptance criteria. "Make search work" is not testable. "Search returns relevant results within 200ms for queries up to 100 characters" is testable.
3. Dependencies are sacred. If Task B truly depends on Task A, mark it. False dependencies slow teams down; missing dependencies cause integration failures.
4. Edge cases are not optional. Every feature has edge cases. If the edge case list is empty, the analysis is incomplete.
5. Parallel = velocity. Maximize parallel tasks. If 4 tasks can be done simultaneously, the phase takes the duration of the longest, not the sum.

Error Handling

Problem	Resolution
Feature description is vague	State assumptions, decompose what's known, mark uncertain tasks with "pending clarification."
Feature is too large (20+ tasks)	Split into multiple features. A feature that takes months is a project, not a feature.
No clear acceptance criteria	Help the user define them: "What does done look like? What would you demo?"
Technical stack unknown	Decompose at the logical level (data model, business logic, API, UI) without implementation specifics.

When NOT to Decompose

Push back if:

• The task is already atomic (single function, single file change) — just do it
• The user wants time estimates, not task breakdown — use estimate-calibrator instead
• The feature is exploratory (research, prototype) — decomposition assumes known scope